#!/usr/bin/env python
"""
UC1541 Virtual filesystem

Author: Roman 'gryf' Dobosz <gryf73@gmail.com>
Date: 2019-09-20
Version: 3.3
Licence: BSD
source: https://bitbucket.org/gryf/uc1541
mirror: https://github.com/gryf/uc1541
"""

import sys
import re
import os
import gzip
from subprocess import Popen, PIPE

if os.getenv('UC1541_DEBUG'):
    import logging
    LOG = logging.getLogger('UC1541')
    LOG.setLevel(logging.DEBUG)
    FILE_HANDLER = logging.FileHandler("/tmp/uc1541.log")
    FILE_FORMATTER = logging.Formatter("%(asctime)s %(levelname)-8s "
                                       "%(lineno)s %(funcName)s - %(message)s")
    FILE_HANDLER.setFormatter(FILE_FORMATTER)
    FILE_HANDLER.setLevel(logging.DEBUG)
    LOG.addHandler(FILE_HANDLER)
else:
    class LOG(object):
        """
        Dummy logger object. Does nothing.
        """
        @classmethod
        def debug(*args, **kwargs):
            pass

        @classmethod
        def info(*args, **kwargs):
            pass

        @classmethod
        def warning(*args, **kwargs):
            pass

        @classmethod
        def error(*args, **kwargs):
            pass

        @classmethod
        def critical(*args, **kwargs):
            pass


SECLEN = 256


def _ord(string_or_int):
    """
    Return an int value for the (possible) string passed in argument. This
    function is for compatibility between python2 and python3, where single
    element in byte string array is a string or an int respectively.
    """
    try:
        return ord(string_or_int)
    except TypeError:
        return string_or_int


def _get_raw(dimage):
    """
    Try to get contents of the D64 image either it's gzip compressed or not.
    """
    raw = None
    with gzip.open(dimage, 'rb') as fobj:
        # Although the common approach with gzipped files is to check the
        # magic number, in this case there is no guarantee that first track
        # does not contain exactly the same byte sequence as the magic number.
        # So the only way left is to actually try to uncompress the file.
        try:
            raw = fobj.read()
        except (IOError, OSError):
            pass
    if not raw:
        with open(dimage, 'rb') as fobj:
            raw = fobj.read()

    return raw


def _get_implementation(disk):
    """
    Check the file under fname and return right class for creating an object
    corresponding for the file
    """
    len_map = {822400: D81,  # 80 tracks
               819200: D81,  # 80 tracks, 3200 error bytes
               349696: D71,  # 70 tracks
               351062: D71,  # 70 tracks, 1366 error bytes
               174848: D64,  # usual d64 disc image, 35 tracks, no errors
               175531: D64,  # 35 track, 683 error bytes
               196608: D64,  # 40 track, no errors
               197376: D64}  # 40 track, 768 error bytes

    if disk[:32].startswith(b'C64'):
        return  # T64

    return len_map.get(len(disk))(disk)


class Disk(object):
    """
    Represent common disk interface
    """
    CHAR_MAP = {32: ' ', 33: '!', 34: '"', 35: '#', 37: '%', 38: '&', 39: "'",
                40: '(', 41: ')', 42: '*', 43: '+', 44: ',', 45: '-', 46: '.',
                47: '/', 48: '0', 49: '1', 50: '2', 51: '3', 52: '4', 53: '5',
                54: '6', 55: '7', 56: '8', 57: '9', 59: ';', 60: '<', 61: '=',
                62: '>', 63: '?', 64: '@', 65: 'a', 66: 'b', 67: 'c', 68: 'd',
                69: 'e', 70: 'f', 71: 'g', 72: 'h', 73: 'i', 74: 'j', 75: 'k',
                76: 'l', 77: 'm', 78: 'n', 79: 'o', 80: 'p', 81: 'q', 82: 'r',
                83: 's', 84: 't', 85: 'u', 86: 'v', 87: 'w', 88: 'x', 89: 'y',
                90: 'z', 91: '[', 93: ']', 97: 'A', 98: 'B', 99: 'C',
                100: 'D', 101: 'E', 102: 'F', 103: 'G', 104: 'H', 105: 'I',
                106: 'J', 107: 'K', 108: 'L', 109: 'M', 110: 'N', 111: 'O',
                112: 'P', 113: 'Q', 114: 'R', 115: 'S', 116: 'T', 117: 'U',
                118: 'V', 119: 'W', 120: 'X', 121: 'Y', 122: 'Z', 193: 'A',
                194: 'B', 195: 'C', 196: 'D', 197: 'E', 198: 'F', 199: 'G',
                200: 'H', 201: 'I', 202: 'J', 203: 'K', 204: 'L', 205: 'M',
                206: 'N', 207: 'O', 208: 'P', 209: 'Q', 210: 'R', 211: 'S',
                212: 'T', 213: 'U', 214: 'V', 215: 'W', 216: 'X', 217: 'Y',
                218: 'Z'}

    FILE_TYPES = {0b000: 'del',
                  0b001: 'seq',
                  0b010: 'prg',
                  0b011: 'usr',
                  0b100: 'rel'}

    DIR_TRACK = 18
    DIR_SECTOR = 1

    def __init__(self, raw):
        """
        Init
        """
        self.raw = raw
        self.current_sector_data = None
        self.next_sector = 0
        self.next_track = None
        self._dir_contents = []
        self._already_done = []

    def _map_filename(self, string):
        """
        Transcode filename to ASCII compatible. Replace not supported
        characters with jokers.
        """

        filename = list()

        for chr_ in string:
            if _ord(chr_) == 160:  # shift+space character; $a0
                break

            character = D64.CHAR_MAP.get(_ord(chr_), '?')
            filename.append(character)

        # special cases
        if filename[0] == "-":
            filename[0] = "?"

        LOG.debug("string: ``%s'' mapped to: ``%s''", string,
                  "".join(filename))
        return "".join(filename)

    def _go_to_next_sector(self):
        """
        Fetch (if exist) next sector from a directory chain
        Return False if the chain ends, True otherwise
        """

        # Well, self.next_sector _should_ have value $FF, but apparently there
        # are the cases where it is not, therefore checking for that will not
        # be performed and value of $00 on the next track will end the
        # directory
        if self.next_track == 0:
            LOG.debug("End of directory")
            return False

        if self.next_track is None:
            LOG.debug("Going to the track: %s, %s", self.DIR_TRACK,
                      self.DIR_SECTOR)
            offset = self._get_offset(self.DIR_TRACK, self.DIR_SECTOR)
        else:
            offset = self._get_offset(self.next_track, self.next_sector)
            LOG.debug("Going to the track: %s,%s", self.next_track,
                      self.next_sector)

        self.current_sector_data = self.raw[offset:offset + SECLEN]

        # Guard for reading data out of bound - that happened for discs which
        # store only raw data, even on directory track
        if not self.current_sector_data:
            return False

        self.next_track = _ord(self.current_sector_data[0])
        self.next_sector = _ord(self.current_sector_data[1])

        if (self.next_track, self.next_sector) in self._already_done:
            # Just a failsafe. Endless loop is not what is expected.
            LOG.debug("Loop in track/sector pointer at %d,%d",
                      self.next_track, self.next_sector)
            self._already_done = []
            return False

        self._already_done.append((self.next_track, self.next_sector))
        LOG.debug("Next track: %s,%s", self.next_track, self.next_sector)
        return True

    def _get_ftype(self, num):
        """
        Get filetype as a string
        """
        return D64.FILE_TYPES.get(int("%d%d%d" % (num & 4 and 1,
                                                  num & 2 and 1,
                                                  num & 1), 2), '???')

    def _get_offset(self, track, sector):
        """
        Return offset (in bytes) for specified track and sector.
        """
        return 0

    def _harvest_entries(self):
        """
        Traverse through sectors and store entries in _dir_contents
        """
        sector = self.current_sector_data
        for dummy in range(8):
            entry = sector[:32]
            ftype = _ord(entry[2])

            if ftype == 0:  # deleted
                sector = sector[32:]
                continue

            type_verbose = self._get_ftype(ftype)

            protect = _ord(entry[2]) & 64 and "<" or " "
            fname = entry[5:21]
            if ftype == 'rel':
                size = _ord(entry[23])
            else:
                size = _ord(entry[30]) + _ord(entry[31]) * 226

            self._dir_contents.append({'fname': self._map_filename(fname),
                                       'ftype': type_verbose,
                                       'size': size,
                                       'protect': protect})
            sector = sector[32:]

    def list_dir(self):
        """
        Return directory list as list of dict with keys:
            fname, ftype, protect and size
        """
        while self._go_to_next_sector():
            self._harvest_entries()

        return self._dir_contents


class D64(Disk):
    """
    Implement d64 directory reader
    """

    def _get_offset(self, track, sector):
        """
        Return offset (in bytes) for specified track and sector.

        Track   Sectors/track   # Tracks
        -----   -------------   ---------
         1-17        21            17
        18-24        19             7
        25-30        18             6
        31-40        17            10
        """
        offset = 0
        truncate_track = 0

        if track > 17:
            offset = 17 * 21 * SECLEN
            truncate_track = 17

        if track > 24:
            offset += 7 * 19 * SECLEN
            truncate_track = 24

        if track > 30:
            offset += 6 * 18 * SECLEN
            truncate_track = 30

        track = track - truncate_track
        offset += track * sector * SECLEN

        return offset


class D71(Disk):
    """
    Implement d71 directory reader
    """

    def _get_offset(self, track, sector):
        """
        Return offset (in bytes) for specified track and sector.

            Track       Sec/trk   # Tracks
        --------------  -------   ---------
         1-17 (side 0)    21         17
        18-24 (side 0)    19          7
        25-30 (side 0)    18          6
        31-35 (side 0)    17          5
        36-52 (side 1)    21         17
        53-59 (side 1)    19          7
        60-65 (side 1)    18          6
        66-70 (side 1)    17          5
        """
        offset = 0
        truncate_track = 0

        if track > 17:
            offset = 17 * 21 * SECLEN
            truncate_track = 17

        if track > 24:
            offset += 7 * 19 * SECLEN
            truncate_track = 24

        if track > 30:
            offset += 6 * 18 * SECLEN
            truncate_track = 30

        if track > 35:
            offset += 5 * 17 * SECLEN
            truncate_track = 35

        if track > 52:
            offset = 17 * 21 * SECLEN
            truncate_track = 17

        if track > 59:
            offset += 7 * 19 * SECLEN
            truncate_track = 24

        if track > 65:
            offset += 6 * 18 * SECLEN
            truncate_track = 30

        track = track - truncate_track
        offset += track * sector * SECLEN

        return offset


class D81(Disk):
    """
    Implement d81 directory reader
    """
    DIR_TRACK = 40
    DIR_SECTOR = 3
    FILE_TYPES = {0b000: 'del',
                  0b001: 'seq',
                  0b010: 'prg',
                  0b011: 'usr',
                  0b100: 'rel',
                  0b101: 'cbm'}

    def _get_offset(self, track, sector):
        """
        Return offset (in bytes) for specified track and sector. In d81 is
        easy, since we have 80 tracks with 40 sectors for 256 bytes each.
        """
        # we wan to go to the beginning (first sector) of the track, not it's
        # max, so that we need to extract its amount.
        return (track * 40 - 40) * SECLEN + sector * SECLEN


class Uc1541(object):
    """
    Class for interact with c1541 program and MC
    """
    PRG = re.compile(r'(\d+)\s+"([^"]*)".+?\s(del|prg|rel|seq|usr)([\s<])')

    def __init__(self, archname):
        self.arch = archname
        self.out = ''
        self.err = ''
        self._verbose = os.getenv("UC1541_VERBOSE", False)
        self._hide_del = os.getenv("UC1541_HIDE_DEL", False)

        self.dirlist = _get_implementation(_get_raw(archname)).list_dir()
        self.file_map = {}
        self.directory = []

    def list(self):
        """
        Output list contents of D64 image.
        Convert filenames to be Unix filesystem friendly
        Add suffix to show user what kind of file do he dealing with.
        """
        LOG.info("List contents of %s", self.arch)
        directory = self._get_dir()

        # If there is an error reading directory, show the reason to the user
        if self.out.startswith("Error"):
            sys.stderr.write(self.out.split("\n")[0] + "\n")
            return 2

        for entry in directory:
            sys.stdout.write("%(perms)s   1 %(uid)-8d %(gid)-8d %(size)8d "
                             "Jan 01 1980 %(display_name)s\n" % entry)
        return 0

    def rm(self, dst):
        """
        Remove file from D64 image
        """
        LOG.info("Removing file %s", dst)
        dst = self._get_masked_fname(dst)

        if not self._call_command('delete', dst=dst):
            return self._show_error()

        return 0

    def copyin(self, dst, src):
        """
        Copy file to the D64 image. Destination filename has to be corrected.
        """
        LOG.info("Copy into D64 %s as %s", src, dst)
        dst = self._correct_fname(dst)

        if not self._call_command('write', src=src, dst=dst):
            return self._show_error()

        return 0

    def copyout(self, src, dst):
        """
        Copy file form the D64 image. Source filename has to be corrected,
        since it's representation differ from the real one inside D64 image.
        """
        LOG.info("Copy form D64 %s as %s", src, dst)
        if not src.endswith(".prg"):
            return "cannot read"

        src = self._get_masked_fname(src)

        if not self._call_command('read', src=src, dst=dst):
            return self._show_error()

        return 0

    def mkdir(self, dirname):
        """Not supported"""
        self.err = "D64 format doesn't support directories"
        return self._show_error()

    def run(self, fname):
        """Not supported"""
        self.err = "Not supported, unless you are using MC on real C64 ;)"
        return self._show_error()

    def _correct_fname(self, fname):
        """
        Return filename with mapped characters, without .prg extension.
        Characters like $, *, + in filenames are perfectly legal, but c1541
        program seem to have issues with it while writing, so it will also be
        replaced.
        """
        char_map = {'|': "/",
                    "\\": "/",
                    "~": " ",
                    "$": "?",
                    "*": "?"}

        if fname.lower().endswith(".prg"):
            fname = fname[:-4]

        new_fname = []
        for char in fname:
            trans = char_map.get(char)
            new_fname.append(trans if trans else char)

        return "".join(new_fname)

    def _get_masked_fname(self, fname):
        """
        Return masked filename with '?' jokers instead of non ASCII
        characters, useful for copying or deleting files with c1541. In case
        of several files with same name exists in directory, only first one
        will be operative (first as appeared in directory).

        Warning! If there are two different names but the only difference is in
        non-ASCII characters (some PET ASCII or control characters) there is
        a risk that one can remove both files.
        """
        directory = self._get_dir()

        for entry in directory:
            if entry['display_name'] == fname:
                return entry['pattern_name']

    def _get_dir(self):
        """
        Retrieve directory via c1541 program
        """
        directory = []

        uid = os.getuid()
        gid = os.getgid()

        if not self._call_command('list'):
            return self._show_error()

        idx = 0
        for line in self.out.split("\n"):
            if Uc1541.PRG.match(line):
                blocks, fname, ext, rw = Uc1541.PRG.match(line).groups()

                if ext == 'del' and self._hide_del:
                    continue

                display_name = ".".join([fname, ext])
                pattern_name = self.dirlist[idx]['fname']

                if '/' in display_name:
                    display_name = display_name.replace('/', '|')

                # workaround for space and dash at the beginning of the
                # filename
                char_map = {' ': '~',
                            '-': '_'}
                display_name = "".join([char_map.get(display_name[0],
                                                     display_name[0]),
                                        display_name[1:]])

                if ext == 'del':
                    perms = "----------"
                else:
                    perms = "-r%s-r--r--" % (rw.strip() and "-" or "w")

                directory.append({'pattern_name': pattern_name,
                                  'display_name': display_name,
                                  'uid': uid,
                                  'gid': gid,
                                  'size': int(blocks) * SECLEN,
                                  'perms': perms})
                idx += 1
        return directory

    def _show_error(self):
        """
        Pass out error output from c1541 execution
        """
        if self._verbose:
            return self.err
        else:
            return 1

    def _call_command(self, cmd, src=None, dst=None):
        """
        Return status of the provided command, which can be one of:
            write
            read
            delete
            dir/list
        """
        command = ['c1541', '-attach', self.arch, '-%s' % cmd]
        if src:
            command.append(src)
        if dst:
            command.append(dst)

        LOG.debug('executing command: %s', ' '.join(command))
        # For some reason using write and delete commands and reading output
        # confuses Python3 beneath MC and as a consequence MC report an
        # error...therefore for those commands let's not use
        # universal_newlines...
        universal_newlines = True
        if cmd in ['delete', 'write']:
            universal_newlines = False
        self.out, self.err = Popen(command,
                                   universal_newlines=universal_newlines,
                                   stdout=PIPE, stderr=PIPE).communicate()

        if self.err:
            LOG.debug('an err: %s', self.err)
        return not self.err


CALL_MAP = {'list': lambda a: Uc1541(a.arch).list(),
            'copyin': lambda a: Uc1541(a.arch).copyin(a.src, a.dst),
            'copyout': lambda a: Uc1541(a.arch).copyout(a.src, a.dst),
            'mkdir': lambda a: Uc1541(a.arch).mkdir(a.dst),
            'rm': lambda a: Uc1541(a.arch).rm(a.dst),
            'run': lambda a: Uc1541(a.arch).run(a.dst)}


def parse_args():
    """Use ArgumentParser to check for script arguments and execute."""
    parser = ArgumentParser()
    subparsers = parser.add_subparsers(help='supported commands',
                                       dest='subcommand')
    subparsers.required = True
    parser_list = subparsers.add_parser('list', help="List contents of D64 "
                                        "image")
    parser_copyin = subparsers.add_parser('copyin', help="Copy file into D64 "
                                          "image")
    parser_copyout = subparsers.add_parser('copyout', help="Copy file out of "
                                           "D64 image")
    parser_rm = subparsers.add_parser('rm', help="Delete file from D64 image")
    parser_mkdir = subparsers.add_parser('mkdir', help="Create directory in "
                                         "archive")
    parser_run = subparsers.add_parser('run', help="Execute archived file")

    parser_list.add_argument('arch', help="D64 Image filename")
    parser_list.set_defaults(func=CALL_MAP['list'])

    parser_copyin.add_argument('arch', help="D64 Image filename")
    parser_copyin.add_argument('src', help="Source filename")
    parser_copyin.add_argument('dst', help="Destination filename (to be "
                               "written into D64 image)")
    parser_copyin.set_defaults(func=CALL_MAP['copyin'])

    parser_copyout.add_argument('arch', help="D64 Image filename")
    parser_copyout.add_argument('src', help="Source filename (to be read from"
                                " D64 image")
    parser_copyout.add_argument('dst', help="Destination filename")
    parser_copyout.set_defaults(func=CALL_MAP['copyout'])

    parser_rm.add_argument('arch', help="D64 Image filename")
    parser_rm.add_argument('dst', help="File inside D64 image to be deleted")
    parser_rm.set_defaults(func=CALL_MAP['rm'])

    parser_mkdir.add_argument('arch', help="archive filename")
    parser_mkdir.add_argument('dst', help="Directory name inside archive to "
                              "be created")
    parser_mkdir.set_defaults(func=CALL_MAP['mkdir'])

    parser_run.add_argument('arch', help="archive filename")
    parser_run.add_argument('dst', help="File to be executed")
    parser_run.set_defaults(func=CALL_MAP['run'])

    args = parser.parse_args()
    return args.func(args)


def no_parse():
    """Failsafe argument "parsing". Note, that it blindly takes positional
    arguments without checking them. In case of wrong arguments it will
    silently exit"""
    try:
        if sys.argv[1] not in ('list', 'copyin', 'copyout', 'rm', 'mkdir',
                               "run"):
            sys.exit(2)
    except IndexError:
        sys.exit(2)

    class Arg(object):
        """Mimic argparse object"""
        dst = None
        src = None
        arch = None

    arg = Arg()

    try:
        arg.arch = sys.argv[2]
        if sys.argv[1] in ('copyin', 'copyout'):
            arg.src = sys.argv[3]
            arg.dst = sys.argv[4]
        elif sys.argv[1] in ('rm', 'run', 'mkdir'):
            arg.dst = sys.argv[3]
    except IndexError:
        sys.exit(2)

    return CALL_MAP[sys.argv[1]](arg)


if __name__ == "__main__":
    LOG.debug("Script params: %s", str(sys.argv))
    try:
        from argparse import ArgumentParser
        PARSE_FUNC = parse_args
    except ImportError:
        PARSE_FUNC = no_parse

    sys.exit(PARSE_FUNC())
